Callao is a city in Macon County, Missouri, United States. The population was 292 at the 2010 census.[6]

Callao was laid out in 1858, a year before the railroad was extended to that point.[7][8] The town most likely took its name from the port city of Callao, Peru. Townsfolk did not know what to call the new town. They hung a map of the world on the wall. Blind folded a man like Pin the Tail on the Donkey, aimed him at the map and his finger landed on Callao, Peru.[9][10] A post office called Callao has been in operation since 1859.[11]